I was also experiencing many "freezes" on the "Updating World" screen on my UX50, but one day, I decided to just let it sit there for a few minutes "frozen" only to find that it just was taking a really long time to update everything. Of course, the cause of this lag was probably because I wouldn't come back to the game for more than a half of a day and it must have had a lot of calculations to make.

Also, I've found that when I play music in the background, VS seems to stay more focused and is in result quicker. Perhaps this is because the playing music causes VS to skip all of the executions for its sounds and music-or I just think that it's faster since I'm entertained while I'm waiting.
HTH
-spaceman